Women Who Run

Even though they’re often hard to figure out, I love women. And I love their physiology. People think it’s a little weird that a guy is so interested in estrogen. It’s not really all that weird. Nearly all scientists that study women’s physiology and many gynecologists are male. So I guess I’m not alone in my fascination with women!

Given that women and men are so different, I’ve always thought it peculiar that all coaches, running magazines, and running books take a one-sex-fits-all approach to training. As a female runner (or a coach of women), here’s 6 quick things you need to know:


Estrogen is the single biggest thing that differentiates you from that guy running next to you in a race. It is a powerful hormone, influencing many aspects of a woman’s physiology, from metabolism to glycogen storage to lung function to bone health. A runner-friendly hormone, times of the month when estrogen is high (just before ovulation at end of follicular phase of your menstrual cycle and middle of luteal phase) are good times to focus on hard workouts and races.

Menstrual Irregularities

Many female runners who train hard and a lot who have a low body fat percentage often experience irregular or even absent menstrual cycles, which reduces estrogen levels. Any disruption to your menstrual cycle can decrease your bone mineral density, increasing the risk for osteoporosis and stress fractures. Estrogen is extremely important in facilitating the absorption of calcium into bones. Female runners with irregular or absent menstruation have significantly lower bone density than those with regular menstruation and even compared to non-athletes. If you’re at risk for a stress fracture because of a loss of estrogen, you need to do everything you can to strengthen your bones and prevent a stress fracture, including adequate intake of calcium and vitamin D and strength training. You may also want to take oral contraceptives, which supply you with estrogen.

Body Temperature

Body temperature changes rhythmically throughout the menstrual cycle, peaking during the luteal phase in response to the surge in progesterone. Progesterone acts on the brain’s hypothalamus (the temperature control center), which increases set-point temperature. A higher body temperature during the luteal phase makes it harder to run in the heat during this phase, as runners don’t begin sweating to dissipate heat until they have reached a higher body temperature. So you may want to avoid long races in the heat during the luteal phase of your cycle.


For most female runners, running through the first two trimesters is completely healthy. Frequent complaints of pregnancy, including nausea, heartburn, insomnia, varicose veins, and leg cramps are reduced in women who remain active during their pregnancy. Exercise during pregnancy has also been associated with a reduced risk of developing certain obstetrical complications, including preeclampsia, pregnancy-induced hypertension, and gestational diabetes. There are a few medical conditions that may prohibit you from running and racing while pregnant: significant heart and lung disease, persistent bleeding in the second and third trimesters, and ruptured membranes.


Women rely more on fat and less on carbohydrate while running at the same pace as men. Because humans’ carbohydrate stores are limited, the difference in metabolism between the sexes gives female runners an advantage for very long endurance activities, during which there is a greater need to conserve carbohydrate and a greater use of fat because of the slower pace.


If you bleed a lot during menstruation, your blood’s hemoglobin concentration may decrease, which can negatively impact your ability to transport oxygen in your blood. Since iron is an important component of hemoglobin, iron loss often accompanies a lot of bleeding. If this happens, you may need to supplement your normal diet with iron. Many female runners exhibit athletic anemia (low blood iron levels due to physical activity), especially if they lose a lot of blood during menstruation. Athletic anemia is very common among female runners, especially those training at altitude.

Don’t forget, through the holidays, you can get a 20% discount on Running for Women, with 10% of sales donated to Susan G. Komen for the Cure. Enter RUNSTRONGWOMAN at checkout!


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